Multiple Endoscopic Perspectives of the Petroclival Region with Multiport Combinations

Objectives: This study aims to provide endoscopic perspectives of the petroclival region (PCR) via several approaches and to demonstrate multiport combinations for surgical applications.

Background: The deeply situated intricate anatomical structures within the PCR leads to significant neurosurgical challenges for tumor excision, despite new approaches introduced in recent decades. Endoscopic-assisted neurosurgery, especially for skull base exposure through craniotomy, has gained popularity owing to superior illumination and visualization. Endoscopy thus can overcome some microsurgical limitations.

Methods: Latex-injected cadaveric specimens were endoscopically dissected using the following approaches: extended endonasal transsphenoidal (EETSA), superolateral transorbital (SLTOA), anterior and posterior transpetrosal (ATPA and PTPA), and retrosigmoid approach (RSA). Adjacent approaches were grouped together for multiport combination study, which included measurement of neurovascular element lengths and attack angles.

Results: From the PCR anterior aspect, the EETSA enables exposure of the entire PCR from medial to bilateral sides, requiring extended nasal preparation and transposition of the pituitary gland, and the petrous or cavernous segments of the internal carotid artery. With the SLTOA, the unilateral superior part of the PCR can be accessed via corridors through the roof of the cavernous sinus and the petrosal ridge, while the contralateral prepontine cistern is accessible through the inferomedial triangle. The ATPA provides direct exposure to the supralateral face of the PCR, with dissection of the cisterns allowing access to the lower part of the PCR. The PTPA exposes the entire lateral aspect of the PCR and, with the assistance of the RSA, can even expose the ipsilateral middle fossa. Endoscopic multiport combinations further enhance maneuverability by increasing exposure angles and operational space ([Figs. 1], [2]).

Conclusion: Several endoscope approaches, including multiport combinations, enhance PCR exposure and provide a degree of surgical freedom. Approach selection is guided by the relationship of the lesions to the PCR.

Fig. 1 According to the definition in this study, the red area represents the “land scope” of PCR on the surface of skull base bone, while the green area stands for that on the surface of brainstem (from ventral and lateral aspects). The purple and light blue areas are marked for the area exposed by each approach (EEA, SLO, ATPA, PTPA, and RSA) on the surface of skull base bone and brainstem, respectively.

Fig. 2 The exposed angles and lengths for some cranial nerves (CN, from III∼VII/VIII) by various multiport combination of endoscopic perspectives. The yellow rounds represent the transverse sections of these nerves, which are surrounded by some curves with various colors that stand for the correspondent approaches according to the results of the exposed angles for approaches (M: medial, L: lateral, A: anterior, P: posterior). The yellow lines stand for the whole lengths of these nerves. The length and location along the nerve long axis exposed by each approach is marked by the correspondent color with some data.

Publication History

Article published online:
07 February 2025